Is that a 13" MacBook Pro with a dual core i5? If so, it is not a very powerful Mac for video editing. There are some limitations with it that keep it from being faster.

The CPU is only dual-core. 4 cores or more is preferable for video rendering, but the 13" MacBook Pro did not have a quad-core option until the current 2018 models.

It has integrated graphics. But for video editing and rendering, discrete graphics are preferred, which is available only on the 15" MacBook Pros. In addition, although your integrated graphics is technically capable of allocating 1.5GB of system RAM for graphics, it can only allocate that much when the maximum 16GB RAM is installed, but your Mac only has 8GB RAM. So your Mac probably doesn't have much RAM left over to allocate to graphics acceleration. (Discrete graphics has its own graphics RAM that doesn't depend on the amount of system RAM installed.)

There are still two things you can check to make sure you're getting the most out of the machine you have. First open Adobe Media Encoder, which makes the proxies.

Look at the Renderer pop-up menu on the right. What is it set to? The slowest setting is Mercury Playback Engine Software Only. If it's possible to choose one of the other options, Mercury Playback Engine GPU Acceleration (Metal) or (OpenCL), try them. If they are not available, your Mac's Intel Iris graphics are too old for graphics acceleration.

You can also try making your own ingest preset for proxy creation, preferably based on Cineform rather than H.264, and lower the bitrate so that it's easier to process. Also, as you create your preset, in the Video tab make sure Hardware Encoding is turned on. But that option only works in the Intel CPUs in newer Macs and PCs so I am not sure if it’s available on yours.

Even if you can do both of those things, they won't work miracles. Because your Mac only has two CPU cores, integrated graphics, and only 8GB RAM, any performance improvement might be modest at best. Also, if the MacBook Pro heats up to maximum temperature and starts running the fans hard while rendering, it may temporarily drop its processing speed to stay within a safe temperature range.